Randowhale and Minnowbooster...Can Someone Please Explain???

I've only been here a short while so can someone please explain what a Randowhale and Minnowbooster are and how they work??

I tried to search these names, but I'm having a hard time finding a clear definition of what they are and why everyone is using them.

From what I can figure, you pay steemdollars for upvotes. Is that it or am I missing something?

Also, is it worth it? Does the money earned by using this "service" outweigh the expenditure??

Thanks for lending a hand to a plankton!